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|
//! This module is responsible for matching a search pattern against a node in the AST. In the
//! process of matching, placeholder values are recorded.
use crate::{
parsing::{Constraint, NodeKind, Placeholder},
resolving::{ResolvedPattern, ResolvedRule, UfcsCallInfo},
SsrMatches,
};
use base_db::FileRange;
use hir::Semantics;
use rustc_hash::FxHashMap;
use std::{cell::Cell, iter::Peekable};
use syntax::ast::{AstNode, AstToken};
use syntax::{ast, SyntaxElement, SyntaxElementChildren, SyntaxKind, SyntaxNode, SyntaxToken};
use test_utils::mark;
// Creates a match error. If we're currently attempting to match some code that we thought we were
// going to match, as indicated by the --debug-snippet flag, then populate the reason field.
macro_rules! match_error {
($e:expr) => {{
MatchFailed {
reason: if recording_match_fail_reasons() {
Some(format!("{}", $e))
} else {
None
}
}
}};
($fmt:expr, $($arg:tt)+) => {{
MatchFailed {
reason: if recording_match_fail_reasons() {
Some(format!($fmt, $($arg)+))
} else {
None
}
}
}};
}
// Fails the current match attempt, recording the supplied reason if we're recording match fail reasons.
macro_rules! fail_match {
($($args:tt)*) => {return Err(match_error!($($args)*))};
}
/// Information about a match that was found.
#[derive(Debug)]
pub struct Match {
pub(crate) range: FileRange,
pub(crate) matched_node: SyntaxNode,
pub(crate) placeholder_values: FxHashMap<Var, PlaceholderMatch>,
pub(crate) ignored_comments: Vec<ast::Comment>,
pub(crate) rule_index: usize,
/// The depth of matched_node.
pub(crate) depth: usize,
// Each path in the template rendered for the module in which the match was found.
pub(crate) rendered_template_paths: FxHashMap<SyntaxNode, hir::ModPath>,
}
/// Represents a `$var` in an SSR query.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub(crate) struct Var(pub String);
/// Information about a placeholder bound in a match.
#[derive(Debug)]
pub(crate) struct PlaceholderMatch {
/// The node that the placeholder matched to. If set, then we'll search for further matches
/// within this node. It isn't set when we match tokens within a macro call's token tree.
pub(crate) node: Option<SyntaxNode>,
pub(crate) range: FileRange,
/// More matches, found within `node`.
pub(crate) inner_matches: SsrMatches,
}
#[derive(Debug)]
pub(crate) struct MatchFailureReason {
pub(crate) reason: String,
}
/// An "error" indicating that matching failed. Use the fail_match! macro to create and return this.
#[derive(Clone)]
pub(crate) struct MatchFailed {
/// The reason why we failed to match. Only present when debug_active true in call to
/// `get_match`.
pub(crate) reason: Option<String>,
}
/// Checks if `code` matches the search pattern found in `search_scope`, returning information about
/// the match, if it does. Since we only do matching in this module and searching is done by the
/// parent module, we don't populate nested matches.
pub(crate) fn get_match(
debug_active: bool,
rule: &ResolvedRule,
code: &SyntaxNode,
restrict_range: &Option<FileRange>,
sema: &Semantics<ra_ide_db::RootDatabase>,
) -> Result<Match, MatchFailed> {
record_match_fails_reasons_scope(debug_active, || {
Matcher::try_match(rule, code, restrict_range, sema)
})
}
/// Checks if our search pattern matches a particular node of the AST.
struct Matcher<'db, 'sema> {
sema: &'sema Semantics<'db, ra_ide_db::RootDatabase>,
/// If any placeholders come from anywhere outside of this range, then the match will be
/// rejected.
restrict_range: Option<FileRange>,
rule: &'sema ResolvedRule,
}
/// Which phase of matching we're currently performing. We do two phases because most attempted
/// matches will fail and it means we can defer more expensive checks to the second phase.
enum Phase<'a> {
/// On the first phase, we perform cheap checks. No state is mutated and nothing is recorded.
First,
/// On the second phase, we construct the `Match`. Things like what placeholders bind to is
/// recorded.
Second(&'a mut Match),
}
impl<'db, 'sema> Matcher<'db, 'sema> {
fn try_match(
rule: &ResolvedRule,
code: &SyntaxNode,
restrict_range: &Option<FileRange>,
sema: &'sema Semantics<'db, ra_ide_db::RootDatabase>,
) -> Result<Match, MatchFailed> {
let match_state = Matcher { sema, restrict_range: restrict_range.clone(), rule };
// First pass at matching, where we check that node types and idents match.
match_state.attempt_match_node(&mut Phase::First, &rule.pattern.node, code)?;
match_state.validate_range(&sema.original_range(code))?;
let mut the_match = Match {
range: sema.original_range(code),
matched_node: code.clone(),
placeholder_values: FxHashMap::default(),
ignored_comments: Vec::new(),
rule_index: rule.index,
depth: 0,
rendered_template_paths: FxHashMap::default(),
};
// Second matching pass, where we record placeholder matches, ignored comments and maybe do
// any other more expensive checks that we didn't want to do on the first pass.
match_state.attempt_match_node(
&mut Phase::Second(&mut the_match),
&rule.pattern.node,
code,
)?;
the_match.depth = sema.ancestors_with_macros(the_match.matched_node.clone()).count();
if let Some(template) = &rule.template {
the_match.render_template_paths(template, sema)?;
}
Ok(the_match)
}
/// Checks that `range` is within the permitted range if any. This is applicable when we're
/// processing a macro expansion and we want to fail the match if we're working with a node that
/// didn't originate from the token tree of the macro call.
fn validate_range(&self, range: &FileRange) -> Result<(), MatchFailed> {
if let Some(restrict_range) = &self.restrict_range {
if restrict_range.file_id != range.file_id
|| !restrict_range.range.contains_range(range.range)
{
fail_match!("Node originated from a macro");
}
}
Ok(())
}
fn attempt_match_node(
&self,
phase: &mut Phase,
pattern: &SyntaxNode,
code: &SyntaxNode,
) -> Result<(), MatchFailed> {
// Handle placeholders.
if let Some(placeholder) = self.get_placeholder(&SyntaxElement::Node(pattern.clone())) {
for constraint in &placeholder.constraints {
self.check_constraint(constraint, code)?;
}
if let Phase::Second(matches_out) = phase {
let original_range = self.sema.original_range(code);
// We validated the range for the node when we started the match, so the placeholder
// probably can't fail range validation, but just to be safe...
self.validate_range(&original_range)?;
matches_out.placeholder_values.insert(
Var(placeholder.ident.to_string()),
PlaceholderMatch::new(code, original_range),
);
}
return Ok(());
}
// We allow a UFCS call to match a method call, provided they resolve to the same function.
if let Some(pattern_ufcs) = self.rule.pattern.ufcs_function_calls.get(pattern) {
if let Some(code) = ast::MethodCallExpr::cast(code.clone()) {
return self.attempt_match_ufcs_to_method_call(phase, pattern_ufcs, &code);
}
if let Some(code) = ast::CallExpr::cast(code.clone()) {
return self.attempt_match_ufcs_to_ufcs(phase, pattern_ufcs, &code);
}
}
if pattern.kind() != code.kind() {
fail_match!(
"Pattern had `{}` ({:?}), code had `{}` ({:?})",
pattern.text(),
pattern.kind(),
code.text(),
code.kind()
);
}
// Some kinds of nodes have special handling. For everything else, we fall back to default
// matching.
match code.kind() {
SyntaxKind::RECORD_EXPR_FIELD_LIST => {
self.attempt_match_record_field_list(phase, pattern, code)
}
SyntaxKind::TOKEN_TREE => self.attempt_match_token_tree(phase, pattern, code),
SyntaxKind::PATH => self.attempt_match_path(phase, pattern, code),
_ => self.attempt_match_node_children(phase, pattern, code),
}
}
fn attempt_match_node_children(
&self,
phase: &mut Phase,
pattern: &SyntaxNode,
code: &SyntaxNode,
) -> Result<(), MatchFailed> {
self.attempt_match_sequences(
phase,
PatternIterator::new(pattern),
code.children_with_tokens(),
)
}
fn attempt_match_sequences(
&self,
phase: &mut Phase,
pattern_it: PatternIterator,
mut code_it: SyntaxElementChildren,
) -> Result<(), MatchFailed> {
let mut pattern_it = pattern_it.peekable();
loop {
match phase.next_non_trivial(&mut code_it) {
None => {
if let Some(p) = pattern_it.next() {
fail_match!("Part of the pattern was unmatched: {:?}", p);
}
return Ok(());
}
Some(SyntaxElement::Token(c)) => {
self.attempt_match_token(phase, &mut pattern_it, &c)?;
}
Some(SyntaxElement::Node(c)) => match pattern_it.next() {
Some(SyntaxElement::Node(p)) => {
self.attempt_match_node(phase, &p, &c)?;
}
Some(p) => fail_match!("Pattern wanted '{}', code has {}", p, c.text()),
None => fail_match!("Pattern reached end, code has {}", c.text()),
},
}
}
}
fn attempt_match_token(
&self,
phase: &mut Phase,
pattern: &mut Peekable<PatternIterator>,
code: &syntax::SyntaxToken,
) -> Result<(), MatchFailed> {
phase.record_ignored_comments(code);
// Ignore whitespace and comments.
if code.kind().is_trivia() {
return Ok(());
}
if let Some(SyntaxElement::Token(p)) = pattern.peek() {
// If the code has a comma and the pattern is about to close something, then accept the
// comma without advancing the pattern. i.e. ignore trailing commas.
if code.kind() == SyntaxKind::COMMA && is_closing_token(p.kind()) {
return Ok(());
}
// Conversely, if the pattern has a comma and the code doesn't, skip that part of the
// pattern and continue to match the code.
if p.kind() == SyntaxKind::COMMA && is_closing_token(code.kind()) {
pattern.next();
}
}
// Consume an element from the pattern and make sure it matches.
match pattern.next() {
Some(SyntaxElement::Token(p)) => {
if p.kind() != code.kind() || p.text() != code.text() {
fail_match!(
"Pattern wanted token '{}' ({:?}), but code had token '{}' ({:?})",
p.text(),
p.kind(),
code.text(),
code.kind()
)
}
}
Some(SyntaxElement::Node(p)) => {
// Not sure if this is actually reachable.
fail_match!(
"Pattern wanted {:?}, but code had token '{}' ({:?})",
p,
code.text(),
code.kind()
);
}
None => {
fail_match!("Pattern exhausted, while code remains: `{}`", code.text());
}
}
Ok(())
}
fn check_constraint(
&self,
constraint: &Constraint,
code: &SyntaxNode,
) -> Result<(), MatchFailed> {
match constraint {
Constraint::Kind(kind) => {
kind.matches(code)?;
}
Constraint::Not(sub) => {
if self.check_constraint(&*sub, code).is_ok() {
fail_match!("Constraint {:?} failed for '{}'", constraint, code.text());
}
}
}
Ok(())
}
/// Paths are matched based on whether they refer to the same thing, even if they're written
/// differently.
fn attempt_match_path(
&self,
phase: &mut Phase,
pattern: &SyntaxNode,
code: &SyntaxNode,
) -> Result<(), MatchFailed> {
if let Some(pattern_resolved) = self.rule.pattern.resolved_paths.get(pattern) {
let pattern_path = ast::Path::cast(pattern.clone()).unwrap();
let code_path = ast::Path::cast(code.clone()).unwrap();
if let (Some(pattern_segment), Some(code_segment)) =
(pattern_path.segment(), code_path.segment())
{
// Match everything within the segment except for the name-ref, which is handled
// separately via comparing what the path resolves to below.
self.attempt_match_opt(
phase,
pattern_segment.generic_arg_list(),
code_segment.generic_arg_list(),
)?;
self.attempt_match_opt(
phase,
pattern_segment.param_list(),
code_segment.param_list(),
)?;
}
if matches!(phase, Phase::Second(_)) {
let resolution = self
.sema
.resolve_path(&code_path)
.ok_or_else(|| match_error!("Failed to resolve path `{}`", code.text()))?;
if pattern_resolved.resolution != resolution {
fail_match!("Pattern had path `{}` code had `{}`", pattern.text(), code.text());
}
}
} else {
return self.attempt_match_node_children(phase, pattern, code);
}
Ok(())
}
fn attempt_match_opt<T: AstNode>(
&self,
phase: &mut Phase,
pattern: Option<T>,
code: Option<T>,
) -> Result<(), MatchFailed> {
match (pattern, code) {
(Some(p), Some(c)) => self.attempt_match_node(phase, &p.syntax(), &c.syntax()),
(None, None) => Ok(()),
(Some(p), None) => fail_match!("Pattern `{}` had nothing to match", p.syntax().text()),
(None, Some(c)) => {
fail_match!("Nothing in pattern to match code `{}`", c.syntax().text())
}
}
}
/// We want to allow the records to match in any order, so we have special matching logic for
/// them.
fn attempt_match_record_field_list(
&self,
phase: &mut Phase,
pattern: &SyntaxNode,
code: &SyntaxNode,
) -> Result<(), MatchFailed> {
// Build a map keyed by field name.
let mut fields_by_name = FxHashMap::default();
for child in code.children() {
if let Some(record) = ast::RecordExprField::cast(child.clone()) {
if let Some(name) = record.field_name() {
fields_by_name.insert(name.text().clone(), child.clone());
}
}
}
for p in pattern.children_with_tokens() {
if let SyntaxElement::Node(p) = p {
if let Some(name_element) = p.first_child_or_token() {
if self.get_placeholder(&name_element).is_some() {
// If the pattern is using placeholders for field names then order
// independence doesn't make sense. Fall back to regular ordered
// matching.
return self.attempt_match_node_children(phase, pattern, code);
}
if let Some(ident) = only_ident(name_element) {
let code_record = fields_by_name.remove(ident.text()).ok_or_else(|| {
match_error!(
"Placeholder has record field '{}', but code doesn't",
ident
)
})?;
self.attempt_match_node(phase, &p, &code_record)?;
}
}
}
}
if let Some(unmatched_fields) = fields_by_name.keys().next() {
fail_match!(
"{} field(s) of a record literal failed to match, starting with {}",
fields_by_name.len(),
unmatched_fields
);
}
Ok(())
}
/// Outside of token trees, a placeholder can only match a single AST node, whereas in a token
/// tree it can match a sequence of tokens. Note, that this code will only be used when the
/// pattern matches the macro invocation. For matches within the macro call, we'll already have
/// expanded the macro.
fn attempt_match_token_tree(
&self,
phase: &mut Phase,
pattern: &SyntaxNode,
code: &syntax::SyntaxNode,
) -> Result<(), MatchFailed> {
let mut pattern = PatternIterator::new(pattern).peekable();
let mut children = code.children_with_tokens();
while let Some(child) = children.next() {
if let Some(placeholder) = pattern.peek().and_then(|p| self.get_placeholder(p)) {
pattern.next();
let next_pattern_token = pattern
.peek()
.and_then(|p| match p {
SyntaxElement::Token(t) => Some(t.clone()),
SyntaxElement::Node(n) => n.first_token(),
})
.map(|p| p.text().to_string());
let first_matched_token = child.clone();
let mut last_matched_token = child;
// Read code tokens util we reach one equal to the next token from our pattern
// or we reach the end of the token tree.
while let Some(next) = children.next() {
match &next {
SyntaxElement::Token(t) => {
if Some(t.to_string()) == next_pattern_token {
pattern.next();
break;
}
}
SyntaxElement::Node(n) => {
if let Some(first_token) = n.first_token() {
if Some(first_token.to_string()) == next_pattern_token {
if let Some(SyntaxElement::Node(p)) = pattern.next() {
// We have a subtree that starts with the next token in our pattern.
self.attempt_match_token_tree(phase, &p, &n)?;
break;
}
}
}
}
};
last_matched_token = next;
}
if let Phase::Second(match_out) = phase {
match_out.placeholder_values.insert(
Var(placeholder.ident.to_string()),
PlaceholderMatch::from_range(FileRange {
file_id: self.sema.original_range(code).file_id,
range: first_matched_token
.text_range()
.cover(last_matched_token.text_range()),
}),
);
}
continue;
}
// Match literal (non-placeholder) tokens.
match child {
SyntaxElement::Token(token) => {
self.attempt_match_token(phase, &mut pattern, &token)?;
}
SyntaxElement::Node(node) => match pattern.next() {
Some(SyntaxElement::Node(p)) => {
self.attempt_match_token_tree(phase, &p, &node)?;
}
Some(SyntaxElement::Token(p)) => fail_match!(
"Pattern has token '{}', code has subtree '{}'",
p.text(),
node.text()
),
None => fail_match!("Pattern has nothing, code has '{}'", node.text()),
},
}
}
if let Some(p) = pattern.next() {
fail_match!("Reached end of token tree in code, but pattern still has {:?}", p);
}
Ok(())
}
fn attempt_match_ufcs_to_method_call(
&self,
phase: &mut Phase,
pattern_ufcs: &UfcsCallInfo,
code: &ast::MethodCallExpr,
) -> Result<(), MatchFailed> {
use ast::ArgListOwner;
let code_resolved_function = self
.sema
.resolve_method_call(code)
.ok_or_else(|| match_error!("Failed to resolve method call"))?;
if pattern_ufcs.function != code_resolved_function {
fail_match!("Method call resolved to a different function");
}
if code_resolved_function.has_self_param(self.sema.db) {
if let (Some(pattern_type), Some(expr)) = (&pattern_ufcs.qualifier_type, &code.expr()) {
self.check_expr_type(pattern_type, expr)?;
}
}
// Check arguments.
let mut pattern_args = pattern_ufcs
.call_expr
.arg_list()
.ok_or_else(|| match_error!("Pattern function call has no args"))?
.args();
self.attempt_match_opt(phase, pattern_args.next(), code.expr())?;
let mut code_args =
code.arg_list().ok_or_else(|| match_error!("Code method call has no args"))?.args();
loop {
match (pattern_args.next(), code_args.next()) {
(None, None) => return Ok(()),
(p, c) => self.attempt_match_opt(phase, p, c)?,
}
}
}
fn attempt_match_ufcs_to_ufcs(
&self,
phase: &mut Phase,
pattern_ufcs: &UfcsCallInfo,
code: &ast::CallExpr,
) -> Result<(), MatchFailed> {
use ast::ArgListOwner;
// Check that the first argument is the expected type.
if let (Some(pattern_type), Some(expr)) = (
&pattern_ufcs.qualifier_type,
&code.arg_list().and_then(|code_args| code_args.args().next()),
) {
self.check_expr_type(pattern_type, expr)?;
}
self.attempt_match_node_children(phase, pattern_ufcs.call_expr.syntax(), code.syntax())
}
fn check_expr_type(
&self,
pattern_type: &hir::Type,
expr: &ast::Expr,
) -> Result<(), MatchFailed> {
use hir::HirDisplay;
let code_type = self.sema.type_of_expr(&expr).ok_or_else(|| {
match_error!("Failed to get receiver type for `{}`", expr.syntax().text())
})?;
if !code_type
.autoderef(self.sema.db)
.any(|deref_code_type| *pattern_type == deref_code_type)
{
fail_match!(
"Pattern type `{}` didn't match code type `{}`",
pattern_type.display(self.sema.db),
code_type.display(self.sema.db)
);
}
Ok(())
}
fn get_placeholder(&self, element: &SyntaxElement) -> Option<&Placeholder> {
only_ident(element.clone()).and_then(|ident| self.rule.get_placeholder(&ident))
}
}
impl Match {
fn render_template_paths(
&mut self,
template: &ResolvedPattern,
sema: &Semantics<ra_ide_db::RootDatabase>,
) -> Result<(), MatchFailed> {
let module = sema
.scope(&self.matched_node)
.module()
.ok_or_else(|| match_error!("Matched node isn't in a module"))?;
for (path, resolved_path) in &template.resolved_paths {
if let hir::PathResolution::Def(module_def) = resolved_path.resolution {
let mod_path = module.find_use_path(sema.db, module_def).ok_or_else(|| {
match_error!("Failed to render template path `{}` at match location")
})?;
self.rendered_template_paths.insert(path.clone(), mod_path);
}
}
Ok(())
}
}
impl Phase<'_> {
fn next_non_trivial(&mut self, code_it: &mut SyntaxElementChildren) -> Option<SyntaxElement> {
loop {
let c = code_it.next();
if let Some(SyntaxElement::Token(t)) = &c {
self.record_ignored_comments(t);
if t.kind().is_trivia() {
continue;
}
}
return c;
}
}
fn record_ignored_comments(&mut self, token: &SyntaxToken) {
if token.kind() == SyntaxKind::COMMENT {
if let Phase::Second(match_out) = self {
if let Some(comment) = ast::Comment::cast(token.clone()) {
match_out.ignored_comments.push(comment);
}
}
}
}
}
fn is_closing_token(kind: SyntaxKind) -> bool {
kind == SyntaxKind::R_PAREN || kind == SyntaxKind::R_CURLY || kind == SyntaxKind::R_BRACK
}
pub(crate) fn record_match_fails_reasons_scope<F, T>(debug_active: bool, f: F) -> T
where
F: Fn() -> T,
{
RECORDING_MATCH_FAIL_REASONS.with(|c| c.set(debug_active));
let res = f();
RECORDING_MATCH_FAIL_REASONS.with(|c| c.set(false));
res
}
// For performance reasons, we don't want to record the reason why every match fails, only the bit
// of code that the user indicated they thought would match. We use a thread local to indicate when
// we are trying to match that bit of code. This saves us having to pass a boolean into all the bits
// of code that can make the decision to not match.
thread_local! {
pub static RECORDING_MATCH_FAIL_REASONS: Cell<bool> = Cell::new(false);
}
fn recording_match_fail_reasons() -> bool {
RECORDING_MATCH_FAIL_REASONS.with(|c| c.get())
}
impl PlaceholderMatch {
fn new(node: &SyntaxNode, range: FileRange) -> Self {
Self { node: Some(node.clone()), range, inner_matches: SsrMatches::default() }
}
fn from_range(range: FileRange) -> Self {
Self { node: None, range, inner_matches: SsrMatches::default() }
}
}
impl NodeKind {
fn matches(&self, node: &SyntaxNode) -> Result<(), MatchFailed> {
let ok = match self {
Self::Literal => {
mark::hit!(literal_constraint);
ast::Literal::can_cast(node.kind())
}
};
if !ok {
fail_match!("Code '{}' isn't of kind {:?}", node.text(), self);
}
Ok(())
}
}
// If `node` contains nothing but an ident then return it, otherwise return None.
fn only_ident(element: SyntaxElement) -> Option<SyntaxToken> {
match element {
SyntaxElement::Token(t) => {
if t.kind() == SyntaxKind::IDENT {
return Some(t);
}
}
SyntaxElement::Node(n) => {
let mut children = n.children_with_tokens();
if let (Some(only_child), None) = (children.next(), children.next()) {
return only_ident(only_child);
}
}
}
None
}
struct PatternIterator {
iter: SyntaxElementChildren,
}
impl Iterator for PatternIterator {
type Item = SyntaxElement;
fn next(&mut self) -> Option<SyntaxElement> {
while let Some(element) = self.iter.next() {
if !element.kind().is_trivia() {
return Some(element);
}
}
None
}
}
impl PatternIterator {
fn new(parent: &SyntaxNode) -> Self {
Self { iter: parent.children_with_tokens() }
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{MatchFinder, SsrRule};
#[test]
fn parse_match_replace() {
let rule: SsrRule = "foo($x) ==>> bar($x)".parse().unwrap();
let input = "fn foo() {} fn bar() {} fn main() { foo(1+2); }";
let (db, position, selections) = crate::tests::single_file(input);
let mut match_finder = MatchFinder::in_context(&db, position, selections);
match_finder.add_rule(rule).unwrap();
let matches = match_finder.matches();
assert_eq!(matches.matches.len(), 1);
assert_eq!(matches.matches[0].matched_node.text(), "foo(1+2)");
assert_eq!(matches.matches[0].placeholder_values.len(), 1);
assert_eq!(
matches.matches[0].placeholder_values[&Var("x".to_string())]
.node
.as_ref()
.unwrap()
.text(),
"1+2"
);
let edits = match_finder.edits();
assert_eq!(edits.len(), 1);
let edit = &edits[0];
let mut after = input.to_string();
edit.edit.apply(&mut after);
assert_eq!(after, "fn foo() {} fn bar() {} fn main() { bar(1+2); }");
}
}
|